Biological Sciences Department, College of Science, King Faisal University, 31982 Hofouf, Saudi Arabia.
Biological Sciences Department, College of Science, King Faisal University, 31982 Hofouf, Saudi Arabia.
Int Immunopharmacol. 2017 Nov;52:342-351. doi: 10.1016/j.intimp.2017.09.015. Epub 2017 Oct 7.
Chronic inflammation in ulcerative colitis (UC) patients is the major risk factor for colitis-associated colon cancer (CAC). Recent evidences have shown that microRNAs (miRNAs) are implicated in CAC pathogenesis. However, the interaction of miRNAs with the transcription factors that alleviate CAC has not been reported.
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or 3,3'-diindolylmethane (DIM) were used to activate aryl hydrocarbon receptor (Ahr) in azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced CAC in mice. Real-time PCR was used to quantify the mRNAs of miRNA and coding genes while western blot and ELISA were used to quantify protein levels. Silencing miRNA was carried out by means of electroporation and locked nucleic acid (LNA)-miRNA.
Inducing CAC in mice upregulated miR-132 expression in the colon, spleen and lymph nodes at all stages of disease development. Activation of Ahr by TCDD or DIM boosted miR-132 expression and alleviated CAC severity by suppression of macrophage infiltration and pro-inflammatory cytokines. Interestingly, TCDD, but not DIM, augmented a cholinergic anti-inflammation by inducing acetylcholinesterase (AChE)-targeting miR-132. This anti-inflammation was manifested by suppressed production of TNF-α, IL-1β and IL-6. Silencing miR-132 in vivo in TCDD-treated mice abrogated the cholinergic anti-inflammation and exacerbated CAC. In addition, inhibition of miR-132 in vitro in CD4 cells and macrophages mitigated the inhibitory effect of TCDD on AChE catalytic activity.
Our findings identify miR-132 as a new molecule implicated in CAC pathogenesis, and reveal that miR-132 mediates the ameliorating effects of TCDD on CAC, suggesting miR-132 as a promising therapeutic candidate to control autoimmune inflammation and tumorigenesis in CAC patients.
溃疡性结肠炎（UC）患者的慢性炎症是结肠炎相关结肠癌（CAC）的主要危险因素。最近的证据表明，microRNAs（miRNAs）参与了 CAC 的发病机制。然而，miRNAs 与缓解 CAC 的转录因子之间的相互作用尚未报道。
用 2,3,7,8-四氯二苯并对二恶英（TCDD）或 3,3'-二吲哚基甲烷（DIM）激活丙烯醛（AOM）/葡聚糖硫酸钠（DSS）诱导的 CAC 小鼠中的芳烃受体（Ahr）。实时 PCR 用于定量 miRNA 和编码基因的 mRNA，而 Western blot 和 ELISA 用于定量蛋白水平。通过电穿孔和锁核酸（LNA）-miRNA 进行 miRNA 沉默。
在疾病发展的所有阶段，诱导 CAC 的小鼠结肠、脾脏和淋巴结中 miR-132 的表达上调。TCDD 或 DIM 激活 Ahr 可增强 miR-132 的表达，并通过抑制巨噬细胞浸润和促炎细胞因子减轻 CAC 的严重程度。有趣的是，TCDD 而非 DIM 通过诱导乙酰胆碱酯酶（AChE）靶向 miR-132 增强了胆碱能抗炎作用。这种抗炎作用表现为 TNF-α、IL-1β 和 IL-6 的产生受到抑制。在 TCDD 处理的小鼠体内沉默 miR-132 可消除胆碱能抗炎作用并加重 CAC。此外，体外在 CD4 细胞和巨噬细胞中抑制 miR-132 可减轻 TCDD 对 AChE 催化活性的抑制作用。
我们的研究结果确定了 miR-132 是 CAC 发病机制中涉及的新分子，并表明 miR-132 介导了 TCDD 对 CAC 的改善作用，提示 miR-132 是控制 CAC 患者自身免疫性炎症和肿瘤发生的有前途的治疗候选物。
